Ranged Attack of Opportunity?

[Castanova]

Assume you're designing a squad-based turn-based tactics game... think Final Fantasy Tactics or JA2 or something. Also assume that you're using some form of Attacks of Opportunity for melee. What is your design decision and rationale for implementing AoOs for ranged weapons?

I think this is a tougher question than melee because any decision you make presents potential problems:

1) Anybody at all is eligible to trigger ranged AoO simply by moving into the ranged attacker's range.

This seems like the idealistic solution but I see issues here. First of all, with multiple ranged attackers on the map, any movement is likely to trigger an onslaught of instant attacks. While perhaps "realistic" this doesn't seem particularly fun unless your goal for your combat design is for everything to revolve around ranged combat sight lines. Second, ranged combat frequently requires ammunition (which you may not want to spend freely) and set-up time (reloading/drawing a bow/etc.) which, again, you may not want to waste on any random enemy walking through your sights.


2) Anybody at all is eligible to trigger ranged AoO simply by moving into the ranged attacker's range, however whoever controls the ranged attacker can choose whether to trigger it.

Seems like it has the benefits of #1 while solving its problems... but it introduces new problems. Mainly, every turn takes an eternity to resolve as you are required to repeatedly deal with AoO prompts when you're not the one taking a turn, and the one taking the turn is required to wait for the enemy to answer to these prompts.


3) The bow-user can be marked as eligible/non-eligible for AoO attacks.

This is a sort of middle-ground between #1 and #2. You don't get assaulted with repetitive prompts and you also don't have ranged attackers necessarily wasting ammo/time. However, it introduces a ton of micromanagement that the player must always remember to take care of before ending their turn lest they suffer irritation.


4) No ranged AoO at all.

Well, that's one way to solve these problems. But then the combat system is internally inconsistent what with melee AoO still available.


5) ????? Any other ideas?

 

[barker_s]

How about a variation of #1, an overwatch? A ranged unit might have a cone-shaped area ahead of where it's faced. Enemies would only be subject to ranged AoO if they crossed that unit's narrow (or wide, depending on the skill perhaps?) "overwatch field". I think that makes sense from a realism standpoint too, because while melee fighters have pretty good awarness of their closest surroundings, ranged fighters would usually focus on a certain direction. It might also force the opposing side to use some clever tactical maneuvers, like flanking and so on.

 

[laclongquan]

Limit it to once a round, or if upgrade, twice. Otherwise battle will revolve around setting the best sniper at most convenient location to swipe enemies in THEIR turns. It is ridiculous that such character can attack more than twice their own capabilities just thank to that feature. Also, make such attack automatic or it would drive player mad.

I will use a JA2 example.

With 25AP, a sniper would be able to shoot twice or thrice a turn depend on the gun. With that abilities, sniper can shoot at as much as 6 targets moving in her line of sight, even if it's just one basic snipe shot (snap), which mean 2-3 times her max AP.

Silent Storm series use another way

Target must appear in ambusher's line of sight. You can trigger interrupt if the ambusher has good interrupt skill compared to the target. You can attack during this chance if you have AP left (from previous turn) for attack. And each attack trigger a chance to recalculate interrupt equation. So you might have a best scout attack with snap shot, 3-4 times, at two different targets because he got good interrupt and quick gun. or you might have a soldier full auto shoot at a target but the interrupt end after 3-4 rounds left the barrel since the second equation make that his abilities not allow longer ambush.

 

[J1M]

This is a question of what an attack of opportunity represents. If we consider the traditional D&D version, it is important to remember that unlike a goofy combat system like Final Fantasy Tactics, characters do not just stand there frozen in time while an enemy is able to walk around them and hit them from behind. A character in melee is assumed to occupy a 5x5 foot region and is both aware of his surroundings and defending himself. This is why there are no 'back attacks', but there are rules for flanking.

An attack of opportunity is triggered not whenever another character moves near a fighter, but when that character chooses to move in a hasty fashion. A careful withdrawal (or advance into a reach weapon) is possible via a 5-foot step.

The type of strike that one is open to during an opportunity attack is that of quick improvisation, not careful setup. This is represented by the fact that it is a basic attack roll and not the full set of actions a character can use on their own turn.

With those facts in mind, what would a ranged opportunity attack look like? It is certainly not a high-precision strike that takes into account wind and air pressure. One of the suggestions above about ranged opportunity attacks requiring a set direction is interesting.

Here are some other possible implementations of ranged opportunity attacks:
-Only triggered when a character steps out into the open. Can not be fired when the moving character has partial cover or another character is in line of sight.
-Only viable at half of maximum weapon range.
-Limit characters to one reaction per turn. Give ranged attackers other desirable reaction choices. (Reload, bonus accuracy on next shot, etc.)
-Instead of a vision cone, limit ranged opportunity attacks to a line of 8 squares. (same number of squares a melee character threatens.)
-Limit the number of opportunity attacks a character can trigger per step or per turn.
-Ranged characters make opportunity attacks at a significant accuracy penalty.
-Ranged opportunity attacks are hard-countered by shields.

The main thing to stay away from is a design that allows players to make choices when it is not their turn. In a table-top game this bogs down play. In a digital game it is an interface nightmare.

 

[Damned Registrations]

I'd just like to point out that while letting enemies walk behind the defender certainly is goofy as fuck from a realism standpoint, it works excellently as a means of emphasizing the importance of terrain and positioning. These things tend to matter far, far less when AoO are in play and characters automatically face their enemies, because the importance of avoiding free attacks far outweighs any minor terrain bonuses. But in something like FFT, getting a character into an important location where they can only be attacked from the front can be a huge advantage, and similarly having special movement abilities to get behind enemies or reach safe locations is also very useful. These things don't matter at all if the enemy in question is just going to turn around and defend himself anyways, you may as well just walk straight at him and slug it out without moving at all.

Also, attacks of opportunity in DnD are traditionally only for melee anyways- they represent blundering into a melee character's active defenses, which isn't really applicable for a ranged attacker (presumably they're busy reloading between attacks, while the melee character is assumed to have been looking for openings to attack the entire time, got whatever his offensive moves were by default, and any AoO were caused by an enemy's blunder. But whether or not you make a blunder isn't going to let someone knock an arrow any faster.

 

[Norfleet]

D&D-wise, this already exists. You can ready an action to shoot in response to a target entering range.

 

[JamesDixon]

I would treat it as a held action and use the rules for regular ranged actions. To do so would unbalance the system and grant ranged characters far greater abilities if they held their actions instead of using them normally. The time period of the weapons in question comes into play. If your system is based upon medieval weapons then an archer would only get x amount of shots from their bow during the held action.

More modern weapons with full auto/3-5 round burst capabilities like the M249 SAW and M4. The M249 LMG can lay down 100 rounds per minute, so starting when someone enters their Line of Sight the LMG would open fire and remain firing for the entire turn. Anyone that enters the firing arc would be subjected to the chance to be hit by 10 rounds from the LMG up until the 100 RPM of the LMG. Thus, for 10 characters entering into the firing arc each one of the characters would be subjected to 10 to hit chances each. Now for the caveat, any character beyond the first can decide to enter the cone of fire or not. This way, the LMG is not overpowered.

For the M4 it would be like the archer's attack with the target being subjected to 3-5 to hit chances.

 

[DramaticPopcorn]

D&D-wise, this already exists. You can ready an action to shoot in response to a target entering range.

Yep, just look at KotC. For Ranged characters there's an opportunity to ready for spellcasting or approach.

 

[Castanova]

But in something like FFT, getting a character into an important location where they can only be attacked from the front can be a huge advantage, and similarly having special movement abilities to get behind enemies or reach safe locations is also very useful. These things don't matter at all if the enemy in question is just going to turn around and defend himself anyways, you may as well just walk straight at him and slug it out without moving at all.

Not sure I 100% agree. Sure, if you put your guy in a great spot, it helps you tremendously against one attack (the guy is forced to walk up and attack head-on). However, you are now screwed for the follow-up because you also must attack him from the front. So you get that FFT-style dance where the attacker always walks around to the target's back or side, attacks, and then the roles are reversed for the next turn.

If you don't have directionality, I think positioning still matters for melee. You want to avoid getting surrounded, basically, while also retaining the option to move elsewhere. Even if you don't have mechanics that give bonuses for surrounding an enemy, you're still physically boxing the guy in and limiting his options.

 

[J1M]

Pretty sad how many codexers can't tell the difference between a readied action and an opportunity attack.

 

[SCO]

A mechanic to make them less important but still nice and automatic is only have ranged AoO when the target is unaware of the attacker, be it from stealth, prone position, the attacker FoV point in a different direction than the attacker when it becomes visible or a combination of these mediated by the character system. Would probably cut down on cheese but still reward ambushes.

Substitute/add other limitations if you want to make it weaker.


edit: another way is a imbalanced system where AoO mainly become the players problem because of some factor and are a very secondary player tactic. For example, Valkyria Chronicles does this, because time to objective is the ranking king and available phase turns can be used multiple times on single characters to reach objectives, so AoO are mainly useful to the enemy that can afford to 'waste' a turn to defend/stay behind cover (not always though).